<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .an{
            width: 200px;
            height: 60px;
            left: 100px;
            top: 100px;
            border: 1px solid #000;
            /* 高度的一半 */
            border-radius: 30px;
            background-color: aquamarine;
            text-align: center;
            line-height: 60px;
        }
    </style>
</head>
<body>
    <div class="an">
        123
    </div>
</body>
</html>